1. Field of the Invention
The present invention relates generally to malfunction warning systems and more particularly pertains to an alarm which will signal the occurrence of a sewer back up.
2. Description of the Prior Art
Because of the growing demand for commercial and private sewer systems in this country and throughout the world, it can be appreciated that there is a tremendous need for efficient and reliable warning systems which indicate sewer malfunctions. In this respect, it is generally well known that sewers occasionally tend to become plugged, thus causing a sewer back up which could result in waste water flooding and severely damaging a dwelling interior. Usually, a dwelling occupant is not aware of the fact that a sewer is plugged until such time as the back up actually floods over into the dwelling space and accordingly, there has been a continuing search for efficient and reliable alarm systems which will provide an early indication of a sewer back up prior to any damage being done to the dwelling space. For example, U.S. Pat. No. 3,774,187, issued to Windham on Nov. 20, 1973, illustrates a sewer back up sensor assembly which includes a float fixedly positionable on the end of a reciprocably removable rod within an existing sewer clean out pipe and being operably connected within an electrically operated alarm circuit. During a sewer back up, the sewer water will rise in the clean out pipe, thus effecting a concurrent rise of the float and rod therein, and once the rod has risen a sufficient distance, an electrical switch is closed with effectively activates the alarm circuit. However, the Windham device is complex in its construction, requiring a plurality of specially manufactured parts to effect an attachment of the same to an existing sewer clean out pipe, and further, no means are provided for quickly and easily testing the circuit to determine the presence of corrosion build up. In this regard, corrosion build up over the electrical contacts of the Windham assembly would cause it to malfunction and such a corrosion build up is an expected and normal occurrence. Additionally, corrosion build up could prevent the upward movement of the rod through its guides so as to present a further possibility of alarm circuit failure.
By the same token, U.S. Pat. No. 4,091,365, issued to Allen on May 23, 1978, discloses a sewer drain alarm unit that includes a ball float suspendible in a sewer clean out pipe which, by its weight, serves to hold a pair of electrical contacts in a spaced apart open relationship. In this respect a pivotal arm is disclosed having a weight on one end and the ball float suspended by a chain on the other, with a magnet attached to the end of the arm supporting the ball float. If a sewer back up occurs, the float will rise within the pipe, thus permitting the magnet to rise and touch a magnetic switch resulting in a closing of the alarm circuit, thereby to signal the presence of the sewer back up. While the Allen alarm unit functions in the manner intended, it is of a complex construction including a specially manufactured cap member, and no means are provided for periodically testing for corrosion build up. Further, the ball float lays against the wall of the clean out pipe which can become very sticky and corroded, so as to possibly prevent the float from rising. Also, the magnet utilized in Allen can become weak in time, to the point of its being unable to activate the magnetic switch. Inasmuch as the sewer pipe may be of a metal construction, the magnet and magnetic switch could also prove to be unreliable.
Accordingly, it can be appreciated that there exists a continuing need for new and improved sewer back up alarms which may be easily and economically manufactured, which are efficient and reliable in their operation, and which may be quickly and easily installed in a sewer clean out pipe. In this regard, the present invention substantially fulfils this need.